how to remove devices from apple provisioning profiles

I have a addhoc iOS application, this app has several associated devices in the Apple provisioning profile. Some of choose devices are not used any longer and I want to remove them. When I clicked the "disable" button I got this warning "disabling this device will invalidate all associated provisioning profiles. You can remove this device from your account at the start of your new membership year", What does the "remove this device from your account at the start of the year" mean. Is this not the way to remove devices? I'm confused...